1. Field of the Invention
The present invention relates to a sheet conveying device for conveying a sheet in an image forming apparatus or an image forming system including the same and more particularly to a sheet conveying device of the type using path selectors and a sheet finisher including the same.
2. Description of the Background Art
A sheet conveying devices of the type including a path that branches off in a plurality of directions is conventional. In this type of sheet conveying device, when the path branches off at two positions by way of example, two path selectors are serially arranged on the path for steering a sheet. However, the problem with this configuration is that the two path selectors positioned one after the other occupy substantial part of the path corresponding to the sum of their widths in the direction of conveyance. Stated another way, the path needs a width corresponding to the total width of the path selectors for steering the sheet. Consequently, a sheet finisher or similar apparatus, which includes the sheet conveying device, increases in width in the right-and-left direction, as seen from the operator's side, increasing the size of the casing of the sheet finisher in the direction parallel to the direction of sheet conveyance.
If the two path selectors are not serially arranged, but are arranged in parallel to each other, then the size of the sheet conveying device can be reduced by the width of one path selector. Parallel arrangement of two path selectors are taught in, e.g., Japanese Patent Laid-Open Publication Nos. 7-315668 and 2000-53302.
More specifically, in Laid-Open Publication No. 7-315668 mentioned above, two parallel path selectors are rotated simultaneously with each other, i.e., not independently of each other. This, however, gives rise to a problem that the path selectors occupy a wide area when rotated, and moreover a solenoid capable of outputting great power is required for driving the path selectors.
In Laid-Open Publication No. 2000-53302 also mentioned above, a first and a second path selector are located at a first and a second branching position, respectively, and interconnected by a first, a second and a third link member. A solenoid actuates the two path selectors via the link members. A third path selector is additionally located at the second branching position and driven about a fulcrum independent of the fulcrum of the second path selector. This configuration, however, has a problem that when the edge of upper one of the second and third path selectors, which are movable about the respective fulcrums, is brought into contact with the upper surface of the lower path selector, the distance between the edges of the two path selectors increases. It is therefore likely that a sheet cannot be accurately conveyed and jams the path. Although this problem may be solved if the edges of the upper and lower path selectors are configured as comb teeth, such comb-teeth edges are apt to catch, when a tab sheet is conveyed, the tab of the sheet. The arrangement taught in the above document will be described more specifically later with reference to the accompanying drawings.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 5-286672, 7-252002 and 2002-154728.